A New Species of Platymantis (Anura: Ranidae) from Quaternary Deposits On Viti Levu, Fiji

Fossil bones of the frog Platymantis are reported for the first time. Platymantis megabotoniviti sp. nov. is described from fossil bones of late Quaternary age from caves on Viti Levu, Fiji, south-west Pacific, where it was associated with fossils of the extant P. vitianus P. vitiensis . The new species is much larger than any extant congeners, and its robust form indicates that it was a ground-dwelling frog. It appears to have become extinct in the late Holocene after humans arrived on Fiji with commensal rodents.     

Iophenoxic Acid as a Long-Term Marker for Wild Boar

ABSTRACT Chemical markers are increasingly used to investigate consumption of baits used to deliver vaccines, toxicants, and contraceptives. We evaluated whether ethyl-iophenoxic acid (Et-IPA) and propyl-iophenoxic acid (Pr-IPA) can be used as long-lasting systemic bait markers for wild boar (Sus scrofa). We presented captive wild boar with baits treated with either Et-IPA or Pr-IPA at 5 mg/kg (low dose), 10 mg/kg (medium dose), and 20 mg/kg (high dose) of body weight. We collected serum from each boar at 5 time points: 5 days, 3 weeks, 6 weeks, 11 weeks, and 39 weeks following ingestion of iophenoxic acid-treated baits. We detected both Et-IPA and Pr-IPA for ≥39 weeks after ingestion. Throughout the trial, the Et-IPA we found in serum was proportional to the amount eaten. At each time point, animals in the high-dose group had significantly more Et-IPA than animals in the low-dose group. We concluded that both compounds can be used as long-lasting markers in wild boar and that Et-IPA can also be employed as quantitative marker to indicate multiple bait uptake. Both compounds have potential applications in the context of vaccination, fertility, and population control campaigns, where baits are used to deliver pharmaceuticals, and in behavioral studies to establish spatial and temporal patterns of bait uptake.     

Osmotic Requirement for Shoot Formation in Tobacco Callus

Tobacco callus grown on medium containing 3% sucrose (w/v) shows optimum growth and produces the highest number of shoots; whereas cultures grown on medium with lower or higher sucrose levels show a reduced growth rate and capacity to form shoots. Cultures grown on a low sucrose containing medium produce a high number of shoots only if the medium is supplemented with mannitol to give the same water potential as that of the 3% sucrose medium. Mannitol cannot replace the sucrose requirement for growth. Increased levels of Bacto Agar, tricarboxylic acid cycle intermediates and amino acids added to the medium do not promote shoot formation or replace the carbohydrate requirement for that process. The success in partially replacing the sucrose requirement for shoot formation with mannitol supports the view that part of the tissue carbohydrate is acting in an osmoregulatory role. This finding is further interpreted in terms of the hypothesis of turgor-driven growth and cell expansion.     

Analysis, purification and quantification of extracellular DNA from aquatic environments

SUMMARY 1. The presence of extracellular DNA, but not RNA, at μg 1⁻¹ concentrations was demonstrated in seawater, river water and in a series of eutrophic lowland ponds.
2. Extracellular DNA in natural waters invariably comprised two major components: one of high molecular weight (>20 kb) derived from viruses, and another of low molecular weight (1–500 bp) and apparently free in solution. Similar species of DNA molecules were produced within 2 weeks in simple laboratory modules.
3. A purification procedure was developed which separated extracellular DNA from other components of dissolved organic matter, and which also separated viral from soluble DNA. Both types of DNA were purified sufficiently to constitute active templates for enzymes used in DNA manipulation.     

Saliva activated transmission (SAT) of Thogoto virus: relationship with vector potential of different haematophagous arthropods

Tick saliva (or salivary gland extract) potentiates the transmission of Thogoto (THO) virus to uninfected ticks feeding on a non-viraemic guinea-pig. This phenomenon has been named saliva activated transmission (SAT). To investigate the potential of different haematophagous arthropods to mediate SAT, guinea-pigs were infested with uninfected R.appendiculatus Neumann nymphs and inoculated with THO virus and salivary gland extract (SGE) derived from a range of ixodid (metastriate and prostriate) or argasid ticks, or mosquitoes; control guinea-pigs were inoculated with virus alone. Enhancement of THO virus transmission was observed only when SGE was derived from metastriate ticks. Comparison with the vector potential of these various arthropod species revealed that enhancement of THO virus transmission was specific for ticks which were competent vectors of the virus. The data indicate a correlation between vector competence and the ability of haematophagous arthropods to mediate SAT of THO virus.     

DIFFERENCES IN THE FORAGING OF JUVENILE AND ADULT BIRDS: THE IMPORTANCE OF DEVELOPMENTAL CONSTRAINTS

Juvenile birds differ from conspecific adults in their diet and methods of prey capture and prey handling. Juvenile-adult differences in foraging result from (1) immaturity of the beak, skeleto-muscular and neurological systems and (2) the time required to learn foraging skills. These conclusions are largely based on field observations. More experimental studies to assess the relative importance of the various constraints are needed.
Juvenile birds appear to be under strong selection to reach adult form and function as rapidly as possible. Remaining differences between juveniles and adults are largely attributable to constraints. In contrast to many other taxa there are few examples in which juvenile-adult differences in foraging have been accentuated by selection on the juvenile behaviours.